1. Field of the Invention
This invention relates to novel chemical compositions for use in chemical vapor deposition. More specifically, it relates to fluorinated copper alkoxides and fluorinated calcium-copper, strontium-copper, and barium-copper alkoxides having superior physical properties for application in chemical vapor deposition to form thin films. The compounds should also be useful for the preparation of calcium, strontium, and barium-copper oxides by sol-gel processes.
Chemical vapor deposition is a process in which one or several precursor compounds and reactant gases are introduced into a reactor in the vapor phase. The reactor consists of a chamber containing the substrate upon which material is deposited from the vapor as a thin film. Most applications of chemical vapor deposition are in the manufacture of electronic components.
The precursor compound, in its original state, may be a gas, a liquid, or a solid. Gaseous precursors are directly introduced into the reactor. Liquids must be vaporized and solids sublimed to form a vapor. The transfer of vapor into the reactor, and the deposition of material from the vapor on the substrate, take place under vacuum. High deposition rates are generally desirable, and these are favored by precursor compounds having a high volatility, i.e. a high vapor pressure at a given temperature or, equivalently, having a given vapor pressure at a low temperature. A low vaporization or sublimation temperature is desirable in part because some precursor compounds thermally decompose at higher temperatures. Liquids and gases are preferred because better control is obtained over the vaporization process.
Sol-gel processes include controlled hydrolysis of the precursor in an organic solvent and heat treatment of the resulting solid product. The compounds of this invention are soluble in most organic solvents and hydrolyse easily.
2. Description of the Prior Art
Metal alkoxides are known to the art. U.S. Pat. No. 4,260,712 describes barium tertiary alkoxides used with organolithium compounds to make polymerization catalysts.
U.S. Pat. No. 4,681,959 describes the preparation of strontium, barium, gallium, indium, boron, yttrium, titanium, zirconium, and hafnium alkoxides.
U.S. Pat. No. 4,717,584 describes a method of manufacturing magnetic thin films under vacuum in a plasma using iron, barium, cobalt, and zinc alkoxides.
Fluorinated metal alkoxides are described by Abbott et al. (Inorg. Chem. 29, No. 3, 1990, 514); Stafford, Willis, Martin, and Chang (Can. J. Chem, 53, 1975, 817; ibid. 55, 1977, 2459; ibid. 55, 1977, 2465); and Loeb et al. (Inorg. Chem.18, No. 11, 1979, 3160), and Willis, C. J. (Coord. Chem. Rev., 1988, 88, 133.)